Based on which parameters do you want to do the redirect? Just based on the URL?
How many redirects do you need?

1) If we are talking about a few rules, I would write Proxy Services and use the routing action to route to the other Proxy Service (note that this is not a real redirect, is a routing)
2) If there are loads of redirect rules and it's just based on URL, you could do this at the load balancer level (before hitting OSB), which will depend on which load balancer you are using

we have an existing system(web page) where users logs in with their username and password(authentication). Once they give the credentials and hit enter we are using OWSM + OSB to authenticate the user and implement SAML assertions to ensure security .

I am able to succeed till this point. And also getting the required response output after implementing saml token policy.

***** Now, However instead of getting the response back, we need to redirect the user to a third-party webpage automatically once the user is authenticated using saml. *****

This is where I am stuck.

Note:
we are using soap wsdl as request(xml). And the output is also in xml format.